An Optical Spectrum Analyzer (OSA) is configured to measure optical power as a function of wavelength. That is, an output of an OSA is a graph of optical power versus wavelength. With respect to optical networking, an OSA can be used on an optical fiber to determine the channels present, to measure channel drift, detect spectral gaps, equalize channel powers, determine the quality of transmitters/modems, determine signal characteristics, etc. In fixed grid optical networks, wavelengths are spaced apart from each other, or in other words, according to a grid defined by International Telecommunication Union (ITU) in ITU-T G.694.1 (February 2012), “Spectral grids for WDM applications: DWDM frequency grid,” the contents of which are incorporated by reference. In flexible grid optical networks, which is also described in ITU Recommendation G.694.1 “Spectral grids for WDM applications: DWDM frequency grid” (February 2012), each signal can be allocated to spectrum with different widths optimized for the bandwidth requirements of the particular bit rate and modulation scheme of the individual channels. With the advent of flexible grid spacing, OSA measurements could be used to optimize spectrum usage and the like. In general, OSA measurements are useful to provide information not readily available related to actual performance over optical fibers.
Conventionally, optical networks and specifically transceivers or optical modems require an external OSA device for spectral measurements. Disadvantageously, external OSAs require test equipment and operators to physically perform the tests, relocate the test equipment, etc. This is expensive and time-consuming. Alternatively, high-resolution Optical Power Monitors (OPMs) have been proposed that may allow for spectral analysis, but this is still external from a specific transmitter and receiver and an expensive alternative. Conventional OPMs would not provide enough resolution for accurate analysis. Further, relying on the line OPMs to provide the OSA measurements requires the line system to be able to share this information with the modem or transceiver, which is only likely in a homogenous vendor installation which is not always possible; particularly in heterogeneous network deployments.